|Publication number||US7203787 B2|
|Application number||US 11/232,996|
|Publication date||Apr 10, 2007|
|Filing date||Sep 23, 2005|
|Priority date||Jan 25, 1999|
|Also published as||US20060020729|
|Publication number||11232996, 232996, US 7203787 B2, US 7203787B2, US-B2-7203787, US7203787 B2, US7203787B2|
|Inventors||Atsushi Nakamura, Koji Fukunaga, Makoto Kobayashi|
|Original Assignee||Canon Kabushiki Kaisha|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (19), Referenced by (1), Classifications (12), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of application Ser. No. 09/490,448 filed Jan. 24, 2000 now abandoned.
1. Field of the Invention
The present invention relates to an information processing system constituted by a plurality of information processing apparatuses connected by an interface such as an IEEE 1394 interface, an information processing apparatus connected to the system, and a method therefor.
2. Description of the Related Art
An interface such as an IEEE 1394 interface can simultaneously connect a plurality of devices such as a DV (Digital Video), DC (Digital Camera), host computer, scanner, and VTR, unlike an interface such as a centronics for one-to-one connection between a host and device, and realize a data communication network and the like by connecting a plurality of devices.
As for the IEEE 1394 interface, each node has a node unique ID to allow identifying each device. This ID is made up of 64 bits, upper 24 bits of which represent the manufacturer ID of a device assigned by the IEEE standard, and lower 40 bits of which can be freely set by the manufacturer. The node unique ID determines a specific ID for one device regardless of the manufacturer and model.
This node unique ID allows specifying a device in data communication in an IEEE 1394 network connected to a plurality of devices.
Display means and the like have been available which represent a plurality of devices in a network using such information and display device information in the network to manage the use of the network and improve the convenience.
Various devices are connected to this network, and many unspecified devices of different manufacturers can be connected. Some devices connected to a communication control bus allow additionally mounting/dismounting an optional device in order to improve the basic performance, expand the function, or change the device arrangement. Some devices can change the device arrangement by the modular structure. When the display means for presenting device information is adopted in an environment where many unspecified devices of different manufacturers are connected, device information such as the manufacturer name and model name of the device main body can be determined from the node unique ID and the like. However, it is difficult to grasp information about optional devices mountable on the device and information about actually connected optional devices.
Also, when the device is not connected to a network (one-to-one connection between the host and device), it is difficult for the user to grasp information about optional devices mountable on the device.
When the display means is adopted, it is hard to make a device displayed on the display match an actually connected device. That is, device information such as the manufacturer name and model name can be displayed by the node unique ID, but the user must specify the device from the manufacturer name and model name. It is therefore difficult to specify devices when a plurality of devices of the same manufacturer and the same model are connected. In some cases, it is hard for the user to determine the kind of device, e.g., whether the device is a printer or digital camera from only the manufacturer name and model name.
In the environment where a plurality of devices are connected, the user can know function information of each device as the device ID, but cannot know the function of a device which has an ID whose function is not known in advance. Further, the user can know only the individual function of each device based upon its ID, so cannot know a new function realized by combining a plurality of devices (e.g., the function of a copying machine by combining a scanner and printer).
Even when the relative connection relationship between devices in the network is displayed, the user must specify them while confirming the physical connection of the IEEE 1394 network with respect to the display contents.
This becomes more difficult when the network is wide and a target device is connected out of the user's sight.
The present invention has been made to overcome the conventional drawbacks, and has as its object to notify the user of information about devices mountable on an apparatus.
It is another object of the present invention to allow the user to easily specify a device which satisfies a desired function in an environment where a plurality of devices are connected.
It is still another object of the present invention to present, to the user, new function information realized by a combination of a plurality of devices and facilitate effective use of the system in an environment where a plurality of devices are connected.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings. An IEEE 1394 serial bus adopted in this embodiment will be explained.
<Overview of IEEE-1394>
The appearance of digital VTRs and DVDs (Digital Video Disks) for home use has been accompanied by the need of transferring a large information quantity of video and audio data (to be referred to as “AV data” hereinafter) in real time. An interface having high-speed data transferability is required to transfer AV data in real time to a personal computer (PC) or transfer AV data to another digital device. An interface that has been developed in view of the foregoing is an IEEE 1394 serial bus (to be simply referred to as a “1394 serial bus”).
These devices can be connected by a mixture of a daisy chaining and node branching. A high degree of freedom in making the connections is possible. Each device has an ID and by recognizing their IDs with each other, the devices construct one network over an area connected by the 1394 serial bus. For example, by connecting devices by one 1394 serial bus cable simply in a daisy chain, each device functions as a relay, and the devices in their entirety construct one network.
The 1394 serial bus has a function of automatically recognizing a device and recognizing the connection status by only connecting the device to the 1394 serial bus cable. In the system shown in
Further, the data transfer speed of the 1394 serial bus is defined to 100, 200 and 400 Mbps. Devices having higher transfer speeds support lower transfer speeds and are compatible with the devices of lower speed. The data transfer modes available are an asynchronous transfer mode for transferring asynchronous data such as control signals, and an isochronous transfer mode for transferring isochronous data such as real-time AV data. In each cycle (usually 125 μs/cycle), the asynchronous data and isochronous data are mixed and transferred in one cycle, while priority is given to transfer of the isochronous data, following transfer of a cycle-start packet (CSP) that indicates the start of the cycle.
A transaction layer 814 of firmware 801 manages data to be transferred (transacted) and issues read, write, and lock instructions. A management layer 815 of the firmware 801 manages the connection statuses and IDs of respective devices connected to the 1394 serial bus, as well as the configuration of the network. The hardware and firmware make up the essential structure of the 1394 serial bus.
An application layer 816 of software 802 changes depending upon the software used. How to transfer data on the interface is defined by a printer or a protocol such as an AV/C protocol.
Addressing a 1394 serial bus is performed in compliance with the standard of IEEE 1212. An address is set using the first 10 bits to specify a bus number and the next six bits to specify a node ID number.
The remaining 48-bit address used in each device is divided into 20 bits and 28 bits, which are used with a 256-Mbyte unit structure. In the first 20-bit address space, 0 to 0×FFFFD are called a memory space; 0×FFFFE, a private space; and 0×FFFFF, a register space. The private space has addresses that can be freely used in the device. The register space has information common to devices connected to the bus, and is used for communication between the respective devices.
A register (CSR core) serving as the core of the CSR architecture is set in the first 512 bytes of the register space. A serial bus register and configuration ROM are respectively set in the next 512 bytes and 1,024 bytes. The remaining bytes form a unit space where a register unique to a device is set.
In general, the node should use only the first 2,048 bytes of the initial unit space in order to simplify the design of different types of bus systems. As a result, the CSR core, the serial bus register, the configuration ROM, and the first 2,048 bytes of the unit space are desirably made up of 4,096 bytes in all.
The foregoing is an overview of the 1394 serial bus. The features of the 1394 serial bus will now be described in greater detail.
<Details of the 1394 Serial Bus>
[Electrical Specifications of the 1394 Serial Bus]
DS-link coding is suited to high-speed serial-data communication, and requires two twisted-pair signal lines. One twisted-pair line sends a data signal, and the other sends a strobe signal. On the receiving side, a clock can be generated by taking the exclusive-OR between the data signal and strobe signal. The DS-link coding scheme exhibits the following effects. (1) When the DS-link coding scheme is used, no clock signal need be mixed in a data signal, and the transfer efficiency is higher than other serial-data transfer schemes. (2) Since a clock signal can be generated, the phase-locked loop (PLL) circuit can be omitted to reduce the scale of the controller LSI circuitry. (3) Information representing an idle state need not be sent when no data need be transferred. This allows setting the transceiver device of each device to a sleep state, thereby reducing the power consumption.
A node unique ID (to be also referred to as a “node ID” hereinafter) is assigned to each device (node) connected to the 1394 serial bus so that the device is recognized as a node constituting a network. For example, when the number of nodes increases/decreases by plugging/unplugging a network device or turning on/of the power source, i.e., the network configuration changes, and a new network configuration must be recognized, a node which has sensed the change transmits a bus-reset signal to the bus to set a mode in which the new network configuration is to be recognized. The change in network configuration is sensed by sensing a change in bias voltage in the connector port 810.
Upon being transmitted a bus-reset signal from a certain node, the physical layer 811 of each node receives the bus-reset signal and, at the same time, reports occurrence of the bus reset to the link layer 812 and sends the bus-reset signal to the other nodes. After all nodes have eventually received the bus-reset signal, a bus-reset sequence is activated. The bus-reset sequence can also be activated when the cable is plugged/unplugged, when the hardware detects network anomalies, or when an instruction is directly issued to the physical layer 811 by host control from the protocol. When the bus-reset sequence is activated, data transfer is temporarily suspended during the bus reset. After the bus reset is completed, data transfer is resumed on the basis of the new network configuration.
[Node-ID Decision Sequence]
In order for each of the nodes to construct the new network configuration after bus reset, an operation for assigning an ID to each node begins. The usual sequence from bus reset to determination of node IDs will be described with reference to the flowcharts of
If the parent-child relationships have been determined, control proceeds to step S104 to decide a root. A node-ID setting operation for providing each node with an ID is carried out at step S105. Node IDs are set in a predetermined node sequence and the setting operation is performed repeatedly until all nodes are determined at step S106 to be provided with IDs.
When the setting of node IDs is completed, the new network configuration will have been recognized at all nodes and a state will be attained in which data transfer between nodes can be carried out. Data transfer thus begins at step S107. The sequence returns to step S101 to monitor generation of a bus-reset signal again.
Immediately after bus reset, nodes that can make declarations of parent-child relationship first are limited to leaf nodes. A node can ascertain whether it is a leaf node from the number of ports confirmed at step S203. That is, a node whose number of ports is “1” is a leaf node. The leaf node declares with respect to a node connected to it that “This node is the child and the other node is the parent” at step S205. This operation then ends.
A node whose number of connected ports is “2 or more” at step S203, i.e., a branch point has “the number of undefined ports >1” immediately after bus reset. As a result, control proceeds to step S206. Data indicative of a branch node is set at the flag FL. This is followed by step S207, at which the node waits for the declaration of the parent-child relationship from another node. Another node makes the declaration of the parent-child relationship and the branch node that received this returns to step S204 to check the number of undefined ports. If the number of undefined ports is “1”, it is possible to declare “This node is a child and the other node is a parent” at step S205 to another node connected to the remaining port. A branch node whose number of undefined ports is still “2 or more” waits for the declaration of the parent-child relationship from another node at step S207.
When any one branch node (or, in exceptional cases, a leaf node because the leaf node did not operate quickly enough to issue the “Child” declaration) indicates “0” as the number of undefined ports, the declarations of the parent-child relationship for the entire network end as a result. The sole node for which the number of undefined ports has become “0”, i.e., which has been determined as a parent for all the nodes sets data indicative of a root node at the flag FL at step S208, and this node is recognized as a root at step S209.
This ends the procedure from bus reset to declaration of the parent-child relationships between all nodes of the network.
A procedure for assigning an ID to each node will now be described. An ID can be first set for a leaf node. Then, IDs are set in the order of a leaf→branch→root from smaller numbers (node number: 0).
At step S301 of
For a leaf node, the number (natural number) of leaf nodes that exist in the network is set to a variable N at step S302. Each leaf then requests the root node to be given a node number at step S303. In a case where there are a plurality of requests, the root node performs arbitration at step S304. The root node assigns a node number to a given node and notifies the remaining nodes of the result indicative of the node number acquisition failure.
A leaf node whose acquisition of an ID ended in failure at step S306 requests a node number again at step S303. A leaf node that has acquired a node number broadcasts the ID information including the acquired node number to inform all nodes of the ID information at step S307. When the broadcast of the ID information ends., the variable N representing the number of leafs is decremented at step S308. Until the variable N is determined to be “0” at step S309, the procedure from steps S303 to S308 is repeated. After all leaf nodes have broadcast their ID information, control proceeds to step S310, at which the ID setting of branch nodes is carried out.
The setting of branch node IDs is performed in a manner similar to that for leaf nodes. The number (natural number) of branch nodes that exist in the network is set to a variable M at step S310. Each branch node then requests the root node to be given a node number at step S311. In response to this request, the root node performs arbitration at step S312 and assigns a given branch node a number that follows those already assigned to leaf nodes. At step S313, the root node notifies a branch node that has failed in acquiring a node number of the result representing the acquisition failure.
A branch node that has been notified of the node number acquisition failure from determination of step S314 requests a node number again at step S311. A branch node that has acquired a node number broadcasts the ID information including the acquired node number to inform all nodes of the ID information at step S315. When the broadcast of the ID information ends, the variable M representing the number of branches is decremented at step S316. Until the variable M is determined to be “0” at step S317, the procedure from steps S311 to S316 is repeated. After all branch nodes have broadcast their ID information, control proceeds to step S318, at which the ID setting of root nodes is carried out.
When processing thus far ends, a node which has not yet acquired any ID is a root node only. The root node sets the smallest number unassigned to another node as the own ID number at step S318 and broadcasts the root ID information at step S319.
The procedure up to the setting of IDs for all nodes ends. A detailed procedure of the node-ID decision sequence will be explained with respect to the network example shown in
The network shown in
In order to recognize the connection status of each node after bus reset, a declaration of the parent-child relationship is made between the ports at which the nodes are directly connected. A “parent” is an upper layer in the hierarchical structure and the “child” is a lower layer. In
Nodes one layer higher have a plurality of connected ports. These nodes are referred to as branches. Among these nodes, those that have received declarations of the parent-child relationship from other nodes issue declarations of the parent-child relationship in succession and to upper nodes. In
Thus, the hierarchical structure as shown in
After the root node is decided, a transition is made to a mode for deciding the node IDs. All nodes have a broadcast function of communicating their own ID information to all other nodes. Note that the ID information is broadcasted as one including the node number, information on the connection position, the number of connected ports or information on the parent-child relationship of each port.
Assignment of node numbers begins from leaf nodes, as described above. Node numbers=0, 1, 2, . . . are assigned to these nodes in regular order. By broadcasting ID information, the node number is recognized as being already assigned.
If all leaf nodes have finished acquiring their node numbers, then operation shifts to branch nodes so that node numbers are assigned to branch nodes after leaf nodes. In a manner similar to that of the leaf nodes, branch nodes to which node numbers have been assigned broadcast their ID information in succession. Finally, the root node broadcasts its own ID information. Hence, the root node always possesses the largest node ID number.
Thus, the ID setting of the entire hierarchical structure ends, the network configuration is reconstructed and the bus initialization operation is completed.
[Control Information for Node Management]
CSR cores shown in
In the CSR architecture, registers concerning the serial bus are set from 0×FFFFF0000200.
Information about the node resource of the serial bus is set at a position starting from 0×FFFFF0000800.
The CSR architecture has a configuration ROM in order to represent the function of each node. This ROM takes a minimum format or general format and is set from 0×FFFFF0000400. As shown in
The general format has information about nodes in a format as shown in
Note that the Bus Info Block in the configuration ROM of the general format includes a 1394 ASCII code and information about whether the node can function as an isochronous resource manager, cycle master, or bus master. The Root Directory includes information indicative of a vendor ID and node function. The Unit Directory includes information indicative of the type of unit and driver software version.
The Root Directory can hold the basic information of the node device.
Information about a software unit supported by the device can be held in a subdirectory (Unit directory) offset from the Root Directory. In general, this subdirectory holds information about a data transfer protocol and command set for performing data communication between devices on the IEEE 1394 bus.
In addition, the configuration ROM can hold device unique information (Node dependent info). This information is held as a Node dependent info directory in the form of a subdirectory offset from the Root Directory.
The configuration ROM can be extended to have a subdirectory (Instance Directory) for storing information about functions supported by the device and accessory information.
Data to be stored in the ROM are assigned with keyvalues in accordance with a predetermined format and rule. By decoding the keyvalues, the type of information can be identified.
Note that the detailed structure of the configuration ROM is described in the ISO/IEC 13213, IEEE Std 1212, and IEEE Std 1394–1995, and a description thereof will be omitted.
[Serial Bus Management]
As shown in
Only one node for performing bus management (to be referred to as a “bus management node” hereinafter) exists on a single bus and provides another node on the serial bus with a management function. The management function includes cycle master control, performance optimization, power management, transfer speed management, and configuration management.
The bus management function is roughly divided into three functions, i.e., a bus manager, isochronous resource manager, and node control. Node control is a management function which enables communication between nodes in the physical layer 811, link layer 812, transaction layer 814, and application. The isochronous resource manager is a management function necessary for transferring isochronous data on the serial bus, and manages assignment of the isochronous data transfer bandwidth and channel number. To perform this management, a bus management node is dynamically selected from nodes having the isochronous resource manager function after bus initialization.
In a configuration in which no bus management node exists on the bus, some functions of the bus management such as power management and cycle master control are executed by a node having the isochronous resource manager function. Further, bus management is a management function for carrying out services for providing an application with a bus control interface, and includes a serial bus control request (SB_CONTROL.request), serial bus event control confirmation (SB_CONTROL.confirmation), and serial bus event indication (SB_EVENT.indication).
The serial bus control request is used-when an application requests bus reset, bus initialization, bus state information, and the like to the bus management node. Serial bus event control confirmation is the result of the serial bus control request, and notified from the bus management node to the application. Serial bus event indication notifies the application from the bus management node of events that occur asynchronously.
[Data Transfer Protocol]
Data transfer on the 1394 serial bus simultaneously includes both isochronous data (isochronous packet) which must be periodically transmitted and asynchronous data (asynchronous packet) for which data transmission/reception at an arbitrary timing is permitted. Further, this data transfer guarantees real-time transfer of isochronous data. In data transfer, bus access is requested prior to transfer, and bus arbitration for granting bus access is executed.
In asynchronous transfer, a transmission node ID and reception node ID are transferred as packet data together with transfer data. The reception node confirms its own node ID, receives a packet, and returns an acknowledge signal to the transmission node. Then, one transaction ends.
In isochronous transfer, the transmission node requests an isochronous channel together with the transfer speed, and transmits a channel ID as packet data together with transfer data. The reception node confirms a desired channel ID and receives the data packet. The number of necessary channels and transfer speed are determined by the application layer 816.
These data transfer protocols are defined by the three, physical layer 811, link layer 812, and transaction layer 814. The physical layer 811 performs a physical/electrical interface with the bus, automatic recognition of node connection, and bus arbitration of bus access between nodes. The link layer 812 performs addressing, data check, packet transmission/reception, and cycle control for isochronous transfer. The transaction layer 814 performs processing concerning asynchronous data. Processing in each layer will be explained.
Bus arbitration in the physical layer 811 will be described.
With a 1394 serial bus, arbitration for bus access is always carried out before data transfer. Respective devices connected to the 1394 serial bus relay signals transferred in the network to construct a logical bus-type network for transmitting the same signal to all devices in the network. Consequently, arbitration is necessary to prevent collision of packets. As a result, only one node can perform transfer at a certain time.
Upon receiving the bus access request, the root node decides which node should be granted access to the bus. Such arbitration is performed solely by the root node. The node that has won the arbitration is granted access to the bus.
A DP (Data Prefix) packet is sent to the node that lost the bus arbitration, thereby informing this node of refusal. The bus access request from the refused node waits for the next arbitration.
The node that won the arbitration and was granted bus access can start transferring data. The flow of bus arbitration will be described with reference to the flowchart of
In order for a node to start data transfer, it is necessary that the bus be in an idle state. In order to confirm that the bus is currently idle following the end of data transfer performed previously, the lapse of a predetermined idle-time gap length (e.g., a subtraction gap) set separately in each transfer mode is detected, and if the predetermined gap length is detected, each node judges that the bus becomes idle. At step S401, each node checks whether a predetermined-gap length corresponding to data to be transferred such as asynchronous data or isochronous data has been detected. As long as the predetermined gap length is not detected, bus access needed to begin transfer cannot be requested.
If the predetermined gap length is detected at step S401, each node determines at step S402 whether there is data to be transferred. If there is such data, then, at step S403, the node sends a bus access request to the root. The signal representing the bus access request eventually arrives at the root while being relayed through each device in the network, as shown in
If the root node receives one or more bus access requests at step S404, then, at step S405, the root node checks the number of nodes that issued access requests. If it is found at step S405 that the number of nodes is one, then this node is provided with the bus access that will be allowed next. If it is found at step S405 that a plurality of nodes issued bus access requests, then the root performs arbitration at step S406 to decide one node that is to be granted bus access. This arbitration operation assures that all devices have fair access to the bus and does not grant access only to the same node every time (fair arbitration).
Root node processing branches at step S407 in accordance with one node granted bus access by arbitration performed at step S406 and other nodes that lost the arbitration. When one node won the arbitration or requested bus access, at step S408, the root sends an enable signal to the one node. The node that has received the enable signal immediately starts transferring data (packet) that is to be transferred (step S410). A node that lost the arbitration is sent the DP (Data Prefix) packet, which represents refusal of the bus access request. Processing for the node which has received the DP packet returns to step S401 in order to request bus access again. Processing for the node that has transferred data at step S410 also returns to step S401.
Transactions are classified into three types, i.e., read transaction, write transaction, and lock transaction.
In read transaction, an initiator (request node) reads out data from a specific address of the memory of a target (response node). In write transaction, the initiator writes data on the specific address of the memory of the target. In lock transaction, the initiator transfers reference data and updated at a to the target. The reference data is combined with data at the target address to form a designation address that designates the specific address of the target. Data at this specific address is updated by update data.
Transaction request (TR_DATA.request) is packet transfer to the response node, and transaction indication (TR_DATA.indication) is an indication that the response node has received a request. Transaction response (TR_DATA.response) is acknowledge transmission, and transaction confirmation (TR_DATA.confirmation) is acknowledge reception.
Asynchronous subaction is asynchronous data transfer.
When bus access is granted by bus arbitration, data is transferred in a packet format. A node that has received the data responds by sending back an acknowledge reception code “ack” or by sending a response packet, after a short gap referred to as an “ack gap”. Here “ack” comprises 4-bit information and a 4-bit checksum. Further, “ack” includes information such as success, busy state, or pending state, and is sent back immediately to the node that was the data transmission source.
Asynchronous transfer is one-to-one communication from a transmission node to a reception node. A packet that has been transferred from a node that was the source of the transfer is delivered to each node in the network. However, since packets other than a node's own packet are ignored, only the node at the destination is read in.
A service in the transaction layer 814 is carried out as a set of transaction request and transaction response shown in
In subaction 1, the initiator transfers a data packet indicative of a write request to the target. The target which has received the data packet sends back “pending” indicative of confirmation information in the form of an acknowledge packet. Then, the request subaction ends.
After a subaction gap is inserted, the target sends in subaction 2 a write response indicating that the data packet does not have any data. The initiator which has received the write response sends back a completion response in the form of an acknowledge packet. Then, the response subaction ends.
The time from the completion of subaction 1 to the start of subaction 2 corresponds to a subaction gap in minimum, and can be prolonged to the maximum wait time set for the node.
Isochronous transfer, which can be said to be the most significant feature of the 1394 serial bus, is suited to the transfer of data that requires real-time transfer, such as AV data. Whereas asynchronous transfer is one-to-one transfer, isochronous transfer can uniformly transfer data from one node that is the source of the transmission to all other nodes by means of a broadcast function.
A plurality of various packets can be transferred in one isochronous cycle upon being distinguished from one another by assigning channel IDs to them in the manner of channel A, channel Band channel C, as shown in
As in the manner of asynchronous transfer, bus arbitration is carried out before transmission of a packet in isochronous transfer. However, since this is not one-to-one communication as in asynchronous transfer, no acknowledge reception code “ack” exists in isochronous transfer.
Further, the “iso gaps” (isochronous gaps) shown in
Transfer over an actual 1394 serial bus can be a mixture of isochronous transfer and asynchronous transfer.
As described above, isochronous transfer is performed at a priority higher than that of asynchronous transfer. The reason for this is that after a CSP is issued, isochronous transfer can be started at a gap (isochronous gap, or “iso gap”) that is shorter than the gap (subaction gap) of an idle interval necessary to start asynchronous transfer. Accordingly, priority is given to isochronous transfer over asynchronous transfer.
In the usual bus cycle shown in
After the operation from arbitration to packet transfer has been repeated a number of times equal to the number of channels given and all isochronous transfers in cycle #m end, asynchronous transfer can be carried out. That is, as a result of idle time becoming equal to the subaction gap that makes asynchronous transfer possible, a node that desires to perform an asynchronous transfer carries out bus arbitration. However, asynchronous transfer can be made only in a case where the subaction gap for activating asynchronous transfer is detected in a period of time from the end of isochronous transfer to the moment (cycle synch) at which the next CSP is to be transferred.
In the cycle #m in
If necessary, isochronous transfer is executed every cycle in order to maintain real-time transfer. As a result of cycle time being shortened, there are also occasions where asynchronous transfer is held over to the-ensuing cycle. Such delay information also is managed by the cycle master.
The IEEE 1394 standard provides the following means as a means for allowing an application to recognize a 1394 network topology in order to create a device map. Note that the topology represents the connection statuses of respective nodes connected to a bus, and is information indicative of the connection status of nodes shown in
1. Topology map information held in the bus manager is read.
2. The topology is estimated from a self ID packet in bus reset.
However, means 1 and 2 can obtain the topology of the cable connection order based upon the child-parent relationship between nodes, but cannot obtain information indicative of the physical positional relationship of nodes (but undesirably obtain information about a port which is not actually mounted).
As another means, information for creating a device map is held in the database of a device other than the configuration ROM. In this case, the means for obtaining various pieces of information depends on protocols for database access, data transfer, and the like.
The configuration ROM itself and the function of reading it are necessarily attached to an IEEE 1394-compliant device. Thus, the device is equipped with a function of storing information about the device position, function, and the like in the configuration ROM of each node and reading information by an application. This allows the application of each node to have a so-called device map display function regardless of specific protocols for database access, data transfer, and the like.
The configuration ROM can store a physical position, function, and the like as node unique information. Such information can be used to realize the device map display function.
In this case, in order for the application to obtain the 1394 network topology based upon the physical positional relationship, the configuration ROM of each node is read in accordance with bus reset or user's request to obtain the 1394 network topology. Alternatively, various pieces of node information such as the function in addition to the physical position of the node may be described in the configuration ROM. By reading the configuration ROM, function information of each node can be attained at the same time as the physical position of the node. When the application is to acquire configuration ROM information of each node, the application uses an API for acquiring arbitrary configuration ROM information of a designated node.
Using this means, the application of a device on the IEEE 1394 network can create various device maps such as a physical topology map and the function map of each node in accordance with application purposes. Further, the user can select a device having a necessary function.
An ink-jet printer as a 1394 device in the first embodiment will be described mainly for the arrangement of a 1394 serial bus interface.
When the print head is mounted, an ink cartridge can be exchanged. A color ink-jet cartridge (CIJC) 10 storing a color ink and a monochrome ink-jet cartridge (MIJC) 20 storing only a black ink are prepared.
The printer can be equipped with an automatic sheet feeder 40 capable of automatically feeding a plurality of sheets. In discharging a sheet being printed, i.e., sheet on the platen, the automatic sheet feeder 40 guides a next sheet to the sheet insertion port of the printer. If the printer senses the sheet by a paper sensor at the sheet insertion port after discharge, the automatic sheet feeder 40 feeds a next sheet so as to set it on the platen. The paper tray of the automatic sheet feeder 40 has a remaining sheet sensor. When the number of sheets set in the sheet feeder becomes lower than a predetermined number, the sensor reacts.
There are prepared two types of automatic sheet feeders mountable on the printer, which are selectively used in accordance with a feedable sheet size. An automatic sheet feeder ASF-A4 is used to feed A4-size sheets, whereas an automatic sheet feeder ASF-A3 is used to feed A3-size sheets.
The print head 2706 is shown in
The ink-jet printer is connected to a device using an IEEE 1394 serial bus. A block serving as a 1394 serial bus interface (to be referred to as a 1394 I/F block hereinafter) is the interface 2701 in
The arrangement of the 1394 I/F block will be explained.
Reference numeral 2801 denotes a link layer control IC (LINK IC) which interfaces the printer main body, controls data transfer of PHY IC, and realizes a link layer function in <Overview of IEEE-1394>. The main functions of this IC are a transmission/reception FIFO function for temporarily storing transmission/reception data via the PHY IC 2802, a function of packeting transmission data, a function of determining whether the PHY IC 2802 is suitable for an assigned channel when reception data has an own node address or is isochronous transfer data, a receiver function of performing error check for the data, and a function of interfacing the printer main body.
The ink-jet printer of the first embodiment has a configuration ROM like the one shown in
Software unit information of each device is stored in Unit directories, and node unique information is stored in a Node dependent info directory.
Basic functions such as a printer function and scanner function that are supported by each device with the current arrangement, or detailed information accessory to the basic functions can be stored in a Instance Directory that is a subdirectory offset from the Root Directory.
The structure of the Instance Directory will be described. The Instance Directory stores basic function information supported by the device on the basis of the device function category regardless of protocols classified in advance. For a device that supports a single function, one basic function information is stored. For a device that supports a plurality of functions, these functions are listed.
Each of the listed functions includes a corresponding Function Set Directory. The Function Set Directory stores pointer information to a Unit directory which stores software information corresponding to each function. Further, the Function Set Directory stores a pointer to a Feature Directory for storing detailed unique information about each function.
As described in <Overview of IEEE-1394>, the last 28 bits out of the address setting of the 1394 serial bus are ensured as the unique data area of each device which can be accessed by another device connected to the serial bus.
Registers concerning the unique operation of the printer main body are set in an area after address 800 h. These registers are physically printer controllers and are set in the ASIC in
Status registers that can monitor the operation status of the printer or control registers that can control the operation status are set in an area after address 1000 h.
A state in which the ink-jet printer having the above arrangement is connected to a host personal computer via an IEEE 1394 bus will be described. Assume that the print head and color ink-jet cartridge are set in the ink-jet printer, and the automatic sheet feeder ASF-A3 capable of feeding A3-size sheets is mounted.
After the two devices are connected, both the computer and personal computer are turned on. Then, bus reset occurs owing to IEEE 1394 characteristics.
In order to automatically assign a node ID in response to bus reset, the two devices start a bus-reset sequence and node-ID decision sequence. Details of these sequences have been described in [Bus-reset sequence] and [Node-ID decision sequence] of <Overview of IEEE-1394>.
Assignment of a node ID is decided through these sequences, and the 1394 bus initialization routine ends. In this case, assume that the personal computer becomes a root node.
After that, the personal computer reads the configuration ROM of a partner node to a connected node at a timing at which information about the connected printer is wanted to be obtained (e.g., when the user requests information about the device connected via the 1394 bus). This state is shown in
As described above, the ROM of the printer stores the Instance Directory, Function Set Directory, and Feature Directory.
The computer first reads out basic information about a minimum bus necessary for communication that is stored in the Root Directory. Then, the computer reads out information about the manufacturer name and model name of the device. If the computer finds a Instance Directory during read of the ROM, the computer reads out the contents. In the first embodiment, this Instance Directory stores basic function category information of the device together with a corresponding keyvalue “99”. As for the ink-jet printer of the first embodiment, a value “Printer” meaning a printer is stored as basic function information. The computer reads this information to recognize that the connected device is a printer.
The Instance Directory also stores pointer information to the Unit directory for storing software information necessary to access the printer function, and stores a pointer to the Feature Directory for storing detailed unique information about each function. The computer reads out these pieces of information to obtain outline information of the device according to the first embodiment as a connected 1394 device.
In the Feature Directory, pieces of information about optional devices which can be bought and mounted on the printer are listed up in accordance with a keyvalue for specifying the type of information and a predetermined format. More specifically, the Feature Directory stores information about a color ink-jet cartridge CIJ10 storing a color ink that is an ink cartridge mountable together with a print head HC100, information about a monochrome ink-jet cartridge MIJ10 storing only a black ink, information about an SC100 as an optional scanner head unit, information about the automatic sheet feeder ASF-A4 for feeding A4-size sheets, and information about the automatic sheet feeder ASF-A3 for feeding A3-size sheets. As for each optional device, the device name and brief description are stored as data.
In addition to the above information, this Feature Directory stores information data of a currently mounted optional device among listed-up optional devices, together with a keyvalue for specifying the optional device.
In this ink-jet printer, as shown in
Subsequent to the Instance Directory, the computer connected in the above-mentioned manner can read the Feature Directory to read out information about optional devices mountable on the ink-jet printer and information about currently mounted optional devices.
As an application on the host computer, the host computer uses a device connection information (device map) application for displaying, on the personal computer, the connection status and device information of a (plurality of) device(s) connected to the computer via the IEEE 1394 bus, and managing and controlling devices.
In the first embodiment, the device map is displayed using the device connection information (device map) display program of displaying the connection status and device information of 1394 devices connected to the computer. Then, information about devices connected to the personal computer is read out from the configuration ROM of each connected device in accordance with the request of the program.
In the first embodiment, the connected ink-jet printer is detected, and its configuration ROM is read. At this time, the above-described information about optional devices can also be read out to create a mounted-device table for the ink-jet printer based upon the Feature Directory shown in
The above processing is shown in the flowchart of
If a Instance Directory is found during read of the configuration ROM, processing proceeds from step S13 to step S14 to obtain a function class (“printer” in the example of
At step S16, the computer obtains software information from the Function Set Directory.
If the Function Set Directory stores an offset value to the Feature Directory, processing proceeds from step S17 to step S18. At step S18, the computer reads out information indicative of optional devices mountable on the printer that is stored in the Feature Directory. At step S19, the computer displays the pieces of information obtained at the respective steps.
For each optional device, the Feature Directory stores a keyvalue representing that the device has already been mounted or a keyvalue representing that the device is not mounted. On the display at step S19, a mounted optional device is displayed with a bold character, and an optional device not mounted is displayed with a smaller italic character, as shown by blocks 3202 and 3203 in
According to the first embodiment, information unique to a device is stored in a predetermined read-only memory area in the device. At the same time, information about mountable optional devices and information about optional devices that have already been mounted are stored as an additional function. Based upon these pieces of information, information about optional devices that have already been mounted is provided as part of the device arrangement, and information about optional devices that are not mounted is provided as non-mounted device information. Thus, the user can easily grasp option information of the device.
A standard communication controller can obtain option information of each device, so that no database and the like are required. Since the standard communication controller can obtain information, option information of a partner device can be obtained even when host protocols are not compatible. This enhances the effects particularly in obtaining information in a network connected to many devices having different upper protocols and communication software applications.
As described above, according to the present invention, the user can easily grasp information about devices mountable on an apparatus.
In the second embodiment, function information is written in the configuration ROM of each device in a network such as an IEEE 1394 network. Various applications for displaying topologies and functions realize their services using the function information of the configuration ROM.
In the network of
The application carries out processing at the start of the application or when it senses bus reset. Until the application senses bus reset, it keeps a sleep state (step S501). At the start of the application or when bus reset occurs, the application stores its own node ID as a variable N (step S502), and increments N by one (step S503). The application compares N with the total number of nodes. If N is equal to or larger than the total number of nodes, the application sets “0” in N (steps S504 and S505). If N is equal to or smaller than the total number of nodes, the application reads the ID and the configuration ROM of the Nth node (steps S504 and S506). In this manner, the application reads configuration ROMs from a node next to the own node. At time when the application reads its own configuration ROM (step S507), the application has read the configuration ROMs of all the nodes in the system. Then, the application creates a function classification table (step S508).
From these function category tables, the application program can determine what function can be realized by combining respective devices currently present on the IEEE 1394 network. The function can determine what combination of devices exhibits the maximum performance.
For example, a copying function can be realized by combining Scanner in
A combination of devices that exhibits the maximum performance can be estimated from the parameters Speed and Quality in
As for function selection (step S602), if the “Function” menu on the application window is selected, as shown in
Assume that “Copy” is selected on the pull-down menu in
If the scanner is selected as a device for inputting an image (step S604), as shown in
In this case, “Printer3” in
Since a combination of devices for realizing the function “Copy” using a plurality of devices is found, condition setting (step S605) for selecting a combination becomes possible, as shown in
If speed-priority output is desired, “Speed” is selected from the menu of the application window, as shown in
If quality-priority output is desired, “Quality” is selected from the menu of the application window, as shown in
As described above, when the display application program of the second embodiment is activated, it reads the configuration ROM of each device in the IEEE 1394 network, creates function tables like the ones in
As information supplied to the application, various pieces of function information in the configuration ROM are used. The second embodiment can therefore provide an information acquisition means by a lower-level part in comparison with communication protocol stacks such as the configuration ROM and the transaction for reading the configuration ROM (read transaction for the IEEE 1394 network). An application for providing information about functions realized by a plurality of devices can be installed without using any special database or database access means defined by an upper protocol.
According to the second embodiment, device function information is written as device unique information in a predetermined read-only memory in each device. Another device in the system, such as a management/display device for displaying device connection information, can read the information to recognize the function of the device. By preparing an appropriate application, it can estimate and find a new function realized by combining the functions of devices.
The function information of each device is searched using a predetermined read-only memory in the device. Especially an IEEE 1394-compliant device can acquire information by only low-level read transaction regardless of the upper protocol. For this reason, installation of software concerning communication and a database can be greatly reduced. This effectively reduces the ROM/RAM size in a device having a small system resource.
As has been described above, according to the present invention, the user can easily specify a device that satisfies a desired function in an environment where a plurality of devices are connected.
In addition, the present invention can present, to the user, function information realized by a plurality of devices in an environment where a plurality of devices are connected. This promotes effective use of the system.
The present invention may be applied to a system constituted by a plurality of devices (e.g., a host computer, interface device, reader, and printer) or an apparatus comprising a single device (e.g., a copying machine or facsimile apparatus).
The object of the present invention is realized even by supplying a storage medium storing software program codes for realizing the functions of the above-described embodiments to a system or apparatus, and causing the computer (or a CPU or MPU) of the system or apparatus to read out and execute the program codes stored in the storage medium.
In this case, the program codes read out from the storage medium realize the functions of the above-described embodiments by themselves, and the storage medium storing the program codes constitutes the present invention.
As a storage medium for supplying the program codes, a floppy disk, hard disk, optical disk, magnetooptical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like can be used.
The functions of the above-described embodiments are realized not only when the readout program codes are executed by the computer but also when the OS (Operating System) running on the computer performs part or all of actual processing on the basis of the instructions of the program codes.
The functions of the above-described embodiments are also realized when the program codes read out from the storage medium are written in the memory of a function expansion board inserted into the computer or a function expansion unit connected to the computer, and the CPU of the function expansion board or function expansion unit performs part or all of actual processing on the basis of the instructions of the program codes.
As many apparently widely different embodiments of the present invention can be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.
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|U.S. Classification||710/306, 710/305, 710/100|
|Cooperative Classification||H04L12/40123, H04L12/40058, H04L12/40078, H04L12/6418|
|European Classification||H04L12/64B, H04L12/40F1, H04L12/40F11, H04L12/40F4|
|May 20, 2008||CC||Certificate of correction|
|Sep 9, 2010||FPAY||Fee payment|
Year of fee payment: 4
|Sep 10, 2014||FPAY||Fee payment|
Year of fee payment: 8